Parking assist system

ABSTRACT

A parking assist system for a vehicle includes the following elements. A parking space width calculator is configured to calculate a parking space width between objects. A parking width comparator is configured to compare the parking space width with the width of a virtual parking region. A movement trace detector is configured to detect a movement trace within the virtual parking region. A target detector is configured to determine whether a target faces at least one side of the virtual parking region other than the side near the vehicle. A parking priority setter is configured to set a parking priority for the virtual parking region based on a movement trace and an object. A display selector is configured to display parking space candidates based on parking priority and instructs a driver to select a parking space candidate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent ApplicationNo. 2021-121762 filed on Jul. 26, 2021, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The disclosure relates to a parking assist system which informs a driverof a parking priority used for selecting one of plural parking spacesdetected in a parking lot where the lines of parking spaces drawn on theroad surface are not recognized.

Hitherto, a parking assist system which assists a driver in parking avehicle within the lines of a parking space in a parking lot so as toreduce the burden on the driver is known. In this type of parking assistsystem, while a driver is driving a vehicle in a parking lot, a controlunit detects options of available parking spaces and displays thedetected options on a monitor. The driver then selects a desired one ofthe parking space options.

Then, the control unit forms a parking guiding route for guiding thevehicle to park in the parking space selected by the driver and guidesthe vehicle to the parking space along the parking guiding route.Alternatively, the driver drives and parks the vehicle byhimself/herself by following the parking guiding route displayed on themonitor.

In the above-described known parking assist system, to let a vehiclepark in a parking space, the lines of available parking spaces are firstdetected. If the road surface in a parking lot is covered with snow ormud after flooding, however, the parking space lines drawn on the roadsurface are difficult to recognize. In such a case, the parking assistsystem may fail to form a parking guiding route for guiding the vehicleto a parking space.

A driver usually wants assistance from a parking assist system undersuch a poor environment where parking space lines are difficult torecognize rather than under a good environment. Japanese UnexaminedPatent Application Publication (JP-A) No. 2006-7875, for example,discloses the following technology. It is first checked whether there isa space for parking a vehicle between two vehicles parked side by side.A gap between the parked vehicles is calculated by subtracting a half ofthe total width of the parked vehicles from the center-to-centerdistance in the widthwise direction of the parked vehicles. If this gapis larger than a value obtained by adding a certain margin to the widthof the vehicle, it is determined that the vehicle can be parked in thisgap. Then, the center of this gap is set to be that of a park-to-beregion and the vehicle is guided to the center of this region.

SUMMARY

An aspect of the disclosure provides a parking assist system configuredto guide a vehicle to a parking capable space in a parking lot. Theparking assist system includes an environment information obtainer, astorage, a parking space width calculator, a parking width comparator, avirtual parking region setter, a movement trace detector, an objectdetector, a parking priority setter, a display selector, and a parkingassister. The environment information obtainer is configured to obtainenvironment information on an environment around the vehicle. Thestorage is configured to store data on a virtual parking region to beused for parking the vehicle. The parking space width calculator isconfigured to calculate a width of a parking space between objects,based on the environment information obtained by the environmentinformation obtainer. The parking width comparator is configured tocompare the width of the parking space with a width of the virtualparking region stored in the storage. The virtual parking region setteris configured to set the virtual parking region in the parking space ina case where the parking width comparator has determined that the widthof the parking space is larger than or equal to the width of the virtualparking region. The movement trace detector is configured to detect amovement trace within the set virtual parking region set by the virtualparking region setter, based on the environment information obtained bythe environment information obtainer. The object detector is configuredto determine whether an object of the objects faces at least one ofsides of the virtual parking region other than a side of the virtualparking region close to the vehicle. The parking priority setter isconfigured to set a parking priority for the virtual parking region inaccordance with the movement trace detected by the movement tracedetector and the object which faces the virtual parking region detectedby the object detector. The display selector is configured to displayparking space candidates together to instruct a driver of the vehicle toselect one of the displayed parking space candidates. The parking spacecandidates includes the parking space candidate obtained by linking thecorresponding parking priority set by the parking priority setter to thecorresponding virtual parking region set by the virtual parking regionsetter. The parking assister is configured to set the parking spacecandidate selected by the driver using the display selector to a targetparking space and to guide the vehicle to the target parking space.

An aspect of the disclosure provides a parking assist system configuredto guide a vehicle to a parking capable space in a parking lot. Theparking assist system includes a sensor, a storage, and circuitry. Thesensor is configured to obtain environment information on an environmentaround the vehicle. The storage is configured to store data on a virtualparking region to be used for parking the vehicle. The circuitry isconfigured to calculate a width of a parking space between objects,based on the environment information obtained by the sensor. Thecircuitry configured to: calculate a width of a parking space betweenobjects, based on the environment information obtained by the sensor;compare the calculated width of the parking space between the objectswith a width of the virtual parking region stored in the storage; setthe virtual parking region in the parking space in a case where thewidth of the parking space is found to be larger than or equal to thewidth of the virtual parking region; detect a movement trace within theset virtual parking region, based on the environment informationobtained by the obtainer; determine whether an object of the objectsfaces at least one of sides of the virtual parking region other than aside of the virtual parking region close to the vehicle; set a parkingpriority for the virtual parking region in accordance with the detectedmovement trace and the detected object which faces the virtual parkingregion;

display parking space candidates together to instruct a driver of thevehicle to select a parking space candidate, the parking spacecandidates include the parking space candidate obtained by linking theparking priority to the virtual parking region; and set the parkingspace candidate selected by the driver to a target parking space toguide the vehicle to the target parking space.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification. The drawings illustrate an exampleembodiment and, together with the specification, serve to describe theprinciples of the disclosure.

FIG. 1 is a schematic block diagram of a parking assist system;

FIG. 2 is a flowchart illustrating a parking assist control routine;

FIG. 3 is a flowchart illustrating a parking assist mode sub-routine;

FIGS. 4 through 6 are a flowchart illustrating a poor-environmentparking assist sub-routine;

FIG. 7A illustrates an example in which the width between adjacentparked vehicles is equal to the width of a virtual parking region forparking a vehicle;

FIG. 7B illustrates an example in which the width between adjacentparked vehicles is larger than the width of a virtual parking region forparking a vehicle;

FIG. 7C illustrates an example in which the width between adjacentparked vehicles is smaller than the width of a virtual parking regionfor parking a vehicle;

FIG. 8 illustrates a state in which parking space candidates aredisplayed on a human machine interface (HMI) monitor;

FIG. 9 is a bird's eye view of the entire parking lot including parkingspace candidates;

FIG. 10 is a plan view illustrating a state in which footprints crosstwo opposing sides of a virtual parking region;

FIG. 11 is a plan view illustrating a state in which footprints crosstwo adjacent sides of a virtual parking region;

FIG. 12 is a plan view illustrating a state in which footprints onlycross the side of a virtual parking region where a vehicle ispositioned;

FIG. 13 is a plan view illustrating a state in which parked vehiclesface three sides of a virtual parking region;

FIG. 14 is a plan view illustrating a state in which tire tracks crosstwo opposing sides of a virtual parking region; and

FIG. 15 is a plan view illustrating a state in which tire tracks crosstwo adjacent sides of a virtual parking region.

DETAILED DESCRIPTION

It is difficult for a driver to park a vehicle always at the sameposition in a parking lot of a store, for example, because the parkingsituation is different depending on the positions of other vehiclesparked in the parking lot. Additionally, the layout of parking spaces ina parking lot varies among individual stores.

As disclosed in JP-A No. 2006-7875, a space for parking a vehicle may bedetected between two vehicles parked side by side. However, if the roadsurface of a parking lot is covered with snow or mud after flooding, forexample, it is not possible to recognize the lines of a parking spacedrawn on the road surface, and it is possible that the detected spacebetween the two parked vehicles be a sidewalk or a driving lane whereparking is prohibited.

In the technology disclosed in JP-A No. 2006-7875, whether a vehicle canpark is determined merely based on the distance of a detected spacebetween adjacent parked vehicles. Hence, a control unit may guide thevehicle to a sidewalk or a driving lane between parked vehicles whereparking is prohibited.

On the other hand, even when the control unit determines that a spacebetween adjacent parked vehicles is likely to be a sidewalk or a drivinglane, a driver may recognize from the surrounding situation that thisspace is apparently a parking space. In this manner, if the driver isprovided with a determination result different from what the driveractually identifies, he/she may be disappointed. Nonetheless, informinga driver of the presence of every single detected space, including aspace determined to be a sidewalk or a driving lane, and asking thedriver whether to select the space may impose a burden on the driver.

It is thus desirable not to ask a driver whether to select a parkingspace every time a parking space between parked vehicles is detectedunder a poor environment where the lines of a parking space are notrecognized. It is also desirable to provide a parking assist system thatcan reduce the burden on a driver by not asking the driver whether toselect a parking space in the above-described manner when assisting thevehicle in parking in a parking space using a parking assist function.

In the following, an embodiment of the disclosure is described in detailwith reference to the accompanying drawings. Note that the followingdescription is directed to an illustrative example of the disclosure andnot to be construed as limiting to the disclosure. Factors including,without limitation, numerical values, shapes, materials, components,positions of the components, and how the components are coupled to eachother are illustrative only and not to be construed as limiting to thedisclosure. Further, elements in the following example embodiment whichare not recited in a most-generic independent claim of the disclosureare optional and may be provided on an as-needed basis. The drawings areschematic and are not intended to be drawn to scale. Throughout thepresent specification and the drawings, elements having substantiallythe same function and configuration are denoted with the same numeralsto avoid any redundant description.

A parking assist system 1 illustrated in FIG. 1 is installed in avehicle M (see FIG. 9 ). The parking assist system 1 includes a drivingassist control unit 11. The driving assist control unit 11 isconstituted by a microcontroller including a central processing unit(CPU), a random access memory (RAM), a read only memory (ROM), arewritable non-volatile memory (such as a flash memory or anelectrically erasable programmable read only memory (EEPROM)), and aperipheral device. In the ROM, programs and fixed data, such as thosefor executing processing by the CPU, are stored. The RAM serves as awork area which is used for the CPU and temporarily stores various itemsof data used by the CPU. The CPU is also called a microprocessor (MPU)or a processor. Instead of a CPU, a graphics processing unit (GPU) or agraph streaming processor (GSP) may be used. Alternatively, a CPU, aGPU, and a GSP may be selectively combined and used.

When a driver has selected a desired assist mode, the driving assistcontrol unit 11 performs driving assist in the selected assist mode.Assist modes provided by the driving assist control unit 11 are adriving assist mode and a parking assist mode.

The driving assist mode is executed by the driving assist control unit11 in the following manner. Based on vehicle position informationobtained by a global navigation satellite system (GNSS) sensor 22 a of amap locator unit 22, which will be discussed later, the driving assistcontrol unit 11 performs map matching to match the position of thevehicle M onto a roadmap stored in a roadmap database 22 b. The drivingassist control unit 11 then causes the vehicle M to autonomously drivealong a preset target traveling road in a self-driving zone. On adriving road where autonomous driving is difficult, the driving assistcontrol unit 11 performs known driving control, such asvehicle-to-vehicle distance control (adaptive cruise control (ACC)),active lane keep (ALK) control, and lane departure prevention (LDP)control, to cause the vehicle M to drive along a driving lane and, if aleading vehicle is detected, to follow the leading vehicle.

After the vehicle M has entered a parking lot, when the driver selectsthe parking assist mode while driving the vehicle M by himself/herselfin the parking lot, the driving assist control unit 11 searches for aspace where the vehicle M can park (hereinafter may also be called aparking capable space) and lets the driver know. When the driver selectsone of the parking capable spaces, the driving assist control unit 11causes the vehicle M to automatically park in the selected space.Alternatively, the driving assist control unit 11 displays a parkingguiding route on a plan view of a vehicle image and a surrounding imagedisplayed on a human machine interface (HMI) monitor 31, so as to assistthe driver in parking the vehicle M in the selected space byhimself/herself. Details of the HMI monitor 31 will be discussed later.

Sensors and units that obtain information on the driving state(including the position and the direction) of the vehicle M andsurrounding environment information of the vehicle M, which are used forexecuting the driving assist mode and the parking assist mode, arecoupled to the input side of the driving assist control unit 11.

In the embodiment, as the sensors and units used for executing thedriving assist mode and the parking assist mode, a front-siderecognition sensor 21, a map locator unit 22, an autonomous drivingsensor 23, a braking sensor 24, a selected position sensor 25, arear-side sensor 26, front-left-side/front-right-side sensors 27, andrear-left-side/rear-right-side sensors 28 are provided. The brakingsensor 24 turns ON a brake pedal by detecting an amount by which thedriver has stepped on the brake pedal. The selected position sensor 25detects a position selected as a result of the driver operating a selectlever of transmission. The rear-side sensor 26 obtains information onthe environment at the rear side of the vehicle M. In one embodiment,the front-side recognition sensor 21, the rear-side sensor 26, thefront-left-side/front-right-side sensors 27, and therear-left-side/rear-right-side sensors 28 may serve as an “environmentinformation obtainer”.

The front-side recognition sensor 21 is an image sensor. In theembodiment, the front-side recognition sensor 21 includes a stereocamera and an image processing unit (IPU) 21 c. The stereo camera isconstituted by a main camera 21 a and a sub-camera 21 b and usescharge-coupled devices (CCDs) or complementary metal oxidesemiconductors (CMOSs), for example, as imaging elements. The maincamera 21 a and the sub-camera 21 b have a predetermined base linelength and are located on a front side of the vehicle M at a positionabove a rear-view mirror and near the windshield. The main camera 21 aand the sub-camera 21 b are disposed horizontally symmetrically alongthe width of the vehicle M with a space therebetween. The front-siderecognition sensor 21 processes, by using the IPU 21 c, an image of apredetermined area indicated by environment information obtained by themain camera 21 a and the sub-camera 21 b and sends the processed imageto the driving assist control unit 11.

The map locator unit 22 includes a GNSS sensor 22 a and a roadmapdatabase 22 b. The GNSS sensor 22 a receives positioning signals emittedfrom multiple positioning satellites so as to obtain positioncoordinates of the vehicle M. The roadmap database 22 b is alarge-capacity storage medium, such as a hard disk drive (HDD), andstores roadmap information. As the roadmap information, the roadmapdatabase 22 b stores various types of road information (such as localroads, highways, freeways, road shapes, road directions, lane widths,and the number of lanes) used for executing the driving assist mode andalso stores static information on parking lots (such as positioninformation of the entrances and exits of parking lots and siteinformation on each parking lot) used for executing the parking assistmode.

The driving assist control unit 11 performs map matching to match theposition coordinates (latitude, longitude, and altitude) of the vehicleM obtained by the GNSS sensor 22 a onto a roadmap indicated by theroadmap information stored in the roadmap database 22 b, therebyestimating the current position of the vehicle M on the roadmap.

The autonomous driving sensor 23 is a sensor set used for allowing thevehicle M to autonomously drive. The autonomous driving sensor 23 isconstituted by sensors, such as a vehicle velocity sensor that detectsthe velocity of the vehicle M, a yaw rate sensor that detects a yaw rateacting on the vehicle M, and a longitudinal acceleration sensor thatdetects the longitudinal acceleration.

The rear-side sensor 26 is constituted by a combination of a monocularcamera using CCDs or CMOSs, for example, as imaging elements and atleast one of an ultrasonic sensor, a millimeter wave radar, a microwaveradar, an infrared sensor, a laser radar, or light detection and ranging(LiDAR). Alternatively, the rear-side sensor 26 may include a stereocamera constituted by a main camera and a sub-camera, as in theabove-described front-side recognition sensor 21.

The front-left-side/front-right-side sensors 27 are constituted by afront-left-side sensor and a front-right-side sensor which arerespectively installed on the left and right ridges of a front bumper ofthe vehicle M, for example, and respectively scan the area from theobliquely front left side to the left side and the area from theobliquely front right side to the right side in a circular sector shape.The rear-left-side/rear-right-side sensors 28 are constituted by arear-left-side sensor and a rear-right-side sensor which arerespectively installed on the left and right ridges of a rear bumper ofthe vehicle M, for example, and respectively scan the area from the rearside to the left side and the area from the rear side to the right side,which are difficult to scan by the front-left-side/front-right-sidesensors 27, in a circular sector shape.

The front-left-side/front-right-side sensors 27 and therear-left-side/rear-right-side sensors 28, which are each constituted bya millimeter radar, a microwave radar, and/or a LiDAR, for example,receive waves reflected by an object (such as a parked vehicle Pv or anouter wall when the parking assist mode is executed) so as to obtainenvironment information, such as the distance from the vehicle M to theobject and the direction of the object.

The driving assist control unit 11 is coupled to the HMI monitor 31. Onthe HMI monitor 31, various screens, such as a mode selection screen anda parking space selection screen (see FIG. 8 ), are displayed. The modeselection screen is a screen for instructing the driver to select one ofthe driving assist mode and the parking assist mode to be executed bythe driving assist control unit 11. On the parking space selectionscreen, parking capable spaces are displayed, together with theassociated parking priorities, and the driver is instructed to selectone of the displayed parking spaces. The HMI monitor 31 may double as amulti-information display of a combination meter or a navigation displaydevice (navigation monitor) of a car navigation system.

A driving control actuator 32 and a notifying device 33 are coupled tothe output side of the driving assist control unit 11. The drivingcontrol actuator 32 is an actuator set including a power actuator, anelectric power steering (EPS) actuator, and a brake actuator, forexample, which assist the driving of the vehicle M. The power actuatorcontrols output from drive sources, such as an engine and an electricmotor. The EPS actuator controls driving of an EPS motor. The brakeactuator adjusts the brake fluid pressure to be applied to a brake wheelcylinder provided in each wheel. The notifying device 33 suppliesvarious types of voice information to the driver while the drivingassist mode or the parking assist mode is being executed.

The driving assist control unit 11 has a parking assist control functionto assist the vehicle M in parking in a parking space on behalf of thedriver or to assist the driver in parking by himself/herself. Forexample, the driving assist control unit 11 performs parking assistcontrol in accordance with a parking assist control routine illustratedin FIG. 2 . This routine is executed at regular intervals after thesystem is started.

In step S1, the driving assist control unit 11 obtains vehicle positioninformation from the map locator unit 22. In step S2, the driving assistcontrol unit 11 obtains surrounding map information on the environmentaround the vehicle M from the map locator unit 22, based on the vehicleposition information.

Then, in step S3, the driving assist control unit 11 performs mapmatching to match the position of the vehicle M onto the surrounding mapso as to check whether the vehicle M has entered a parking lot. If thevehicle M is found to have entered a parking lot, the driving assistcontrol unit 11 proceeds to step S4. If the vehicle M has not entered aparking lot, the driving assist control unit 11 exits from the routine.

In step S4, the driving assist control unit 11 causes the notifyingdevice 33 to output a voice message to check with the driver aboutwhether to set the assist mode to the parking assist mode, and alsodisplays the mode selection screen on the HMI monitor 31. Then, in stepS5, the driving assist control unit 11 determines whether the driver hasselected the parking assist mode. If the driver has selected the parkingassist mode, the driving assist control unit 11 proceeds to step S6. Ifthe driver has not selected the parking assist mode after the lapse of apredetermined time after the voice message is output or if the driverhas selected manual driving on the HMI monitor 31, the driving assistcontrol unit 11 exits from the routine.

In step S6, the driving assist control unit 11 executes the parkingassist mode and exits from the routine. The parking assist mode isexecuted in accordance with a parking assist mode sub-routineillustrated in FIG. 3 . In this sub-routine, in step S11, the drivingassist control unit 11 obtains front-side environment information fromthe front-side recognition sensor 21 andfront-left-side/front-right-side environment information from thefront-left-side/front-right-side sensors 27.

Then, in step S12, from the obtained front-side environment informationand front-left-side/front-right-side environment information, thedriving assist control unit 11 checks whether the lines of parkingspaces drawn on the road surface are being recognized. For example,based on the front-side environment information obtained from thefront-side recognition sensor 21 and thefront-left-side/front-right-side environment information obtained fromthe front-left-side/front-right-side sensors 27, the driving assistcontrol unit 11 recognizes the parking space lines from the luminancedifference between the road surface and the edges of the parking spacelines or a change in the intensity (reflectance) of light or wavesreflected by the road surface and the parking space lines.

If it is determined in step S12 that the parking space lines arerecognized, the driving assist control unit 11 proceeds to step S13. Instep S13, the driving assist control unit 11 executes good-environmentparking assist processing and then exits from the routine.Good-environment parking assist processing is the same as known parkingassist processing for guiding a vehicle to a parking space based onparking space lines, and an explanation thereof will thus be omitted.

Conversely, if it is determined in step S12 that the parking space linesare not recognized because the road surface is covered with snow or mud,for example, the driving assist control unit 11 proceeds to step S14. Instep S14, the driving assist control unit 11 executes poor-environmentparking assist processing and exits from the routine. Poor-environmentparking assist processing is executed in accordance with apoor-environment parking assist sub-routine illustrated in FIGS. 4through 6 .

In this sub-routine, in step S21, the driving assist control unit 11first reads a virtual parking region 41. Data on the virtual parkingregion 41 is stored in advance in a storage, such as a ROM or anon-volatile memory, as fixed data. The virtual parking region 41 isused as a reference to check whether the vehicle M can be parked in acertain parking space under a poor environment. For example, asillustrated in FIGS. 7A through 7C, the virtual parking region 41 has arectangular shape having four sides perpendicular to each other. Thefront-back sides of the virtual parking region 41 are set to be thefront-back length of the vehicle M, while the left-right sides are setto have a sufficient parking width Ws. The sufficient parking width Wsis determined by adding an allowance width to the width of the vehicleM.

Then, in step S22, the driving assist control unit 11 detects the widthof a parking space (parking space width) Wp. The parking space width Wpis detected in the following manner. Based on the front-side environmentinformation obtained from the front-side recognition sensor 21 and thefront-left-side/front-right-side environment information obtained fromthe front-left-side/front-right-side sensors 27, objects, such asvehicles parked side by side (parked vehicles) Pv (see FIG. 9 ) andouter walls, are recognized, and the widths of the recognized objects(parked vehicles Pv and outer walls) and the forward distance from thevehicle M to each of the recognized objects are determined. From thedetermined widths and distances, the distance between objects adjacentto each other (parking space width) is calculated. In one embodiment,processing in step S22 may correspond to processing of a “parking spacewidth calculator”.

Then, the driving assist control unit 11 proceeds to step S23 to comparethe parking space width Wp with the sufficient parking width Ws. If theparking space width Wp is greater than or equal to the sufficientparking width Ws (Wp≥Ws), the driving assist control unit 11 determinesthat this parking space is sufficient for parking the vehicle M andproceeds to step S24. Conversely, if the parking space width Wp issmaller than the sufficient parking width Ws (Wp<Ws), the driving assistcontrol unit 11 determines that this parking space is not sufficient forparking the vehicle M and proceeds to step S36. In one embodiment,processing in step S23 may correspond to processing of a “parking widthcomparator”.

In step S24, the driving assist control unit 11 sets the virtual parkingregion 41 in the parking space and proceeds to step S25. The virtualparking region 41 is set so that the widthwise center of the virtualparking region 41 matches that of the parking space and that the frontside of the virtual parking region 41 close to the vehicle M becomesflush with the forward edges of the adjacent objects. In one embodiment,processing in step S24 may correspond to processing of a “virtualparking region setter”.

If, for example, the distance between the objects (parking space widthWp) is twice as large as the sufficient parking width Ws or even larger,multiple virtual parking regions 41 that can be accommodated in thisparking space are set at regular intervals. If it is found in step S23that the distance between the parked vehicles Pv is wide enough toaccommodate three or more virtual parking regions 41, it means that thisparking space is too large and the driving assist control unit 11 mayproceed to step S36 without setting a virtual parking region 41.

In a known driving assist control unit, every time a virtual parkingregion 41 is set in step S24, it is displayed on the HMI monitor 31 andoutputs a voice message to check with the driver about whether toautomatically park the vehicle M in this virtual paring region 41. Thatis, the known driving assist control unit makes the driver check theparking position every time a virtual parking region 41 is set, whichincreases the number of selection times for the driver and becomesburdensome. In contrast, in the embodiment, after all virtual parkingregions 41 are set based on the front-side environment information andfront-left-side/front-right-side environment information, they aredisplayed together on the HMI monitor 31, as in steps S36 and S37, whichwill be discussed later. This can decrease the number of selection timesfor the driver before the driver finally selects a desired parkingposition.

The driving assist control unit 11 then proceeds to step S25. In stepsS25 through S35, the parking priority for the virtual parking region 41set in step S24 is determined. In step S25, based on the front-sideenvironment information obtained from the front-side recognition sensor21 and the front-left-side/front-right-side environment informationobtained from the front-left-side/front-right-side sensors 27, it isdetermined whether footprints 51 are detected as a movement trace withinthe virtual parking region 41 set in step S24. Footprints 51 aredetected in the following manner, for example. Based on the obtainedfront-side environment information and front-left-side/front-right-sideenvironment information, the luminance difference generated on steps(edges) on the snow surface or mud surface due to the presence ofpossible footprints or a change in the intensity (reflectance) of lightor waves reflected by the snow surface or mud surface is found. Then,based on the luminance difference or reflectance, known patternmatching, for example, is performed on a series of feature pointsrepresenting the outlines of possible footprints, thereby recognizingthe footprints 51. In one embodiment, processing in step S25 describedabove and processing in step S31, which will be discussed later, maycorrespond to processing of a “movement trace detector”.

If footprints 51 are detected within the virtual parking region 41, thedriving assist control unit 11 proceeds to step S26. If no footprints 51are detected, the driving assist control unit 11 proceeds to step S36.In step S25, the number of footprints 51 within the virtual parkingregion 41 may be counted. If the number of footprints 51 exceeds apreset threshold, which is used for determining whether the virtualparking region 41 is a sidewalk, the driving assist control unit 11 mayproceed to step S26. If the number of footprints 51 is lower than thepreset threshold, the driving assist control unit 11 may proceed to stepS31.

In step S26, the driving assist control unit 11 checks which side of thevirtual parking region 41 an object faces, based on the front-sideenvironment information and front-left-side/front-right-side environmentinformation. If an object faces each of two sides of the virtual parkingregion 41 other than the side close to the vehicle M, the driving assistcontrol unit 11 proceeds to step S27. If an object faces each of threesides or an object faces one side of the virtual parking region 41 otherthan the side close to the vehicle M, the driving assist control unit 11branches off to step S28. There are two modes in which an object (parkedvehicle Pv in FIGS. 10 and 11 ) faces each of two sides of the virtualparking region 41 other than the side close to the vehicle M. One modeis that, as illustrated in FIG. 10 , an object (parked vehicle Pv inFIG. 10 ) faces each of two sides 41 b adjacent to a side 41 a close tothe vehicle M.

The other mode is that, as illustrated in FIG. 11 , an object (parkedvehicle Pv in FIG. 11 ) faces one of the two sides 41 b adjacent to theside 41 a close to the vehicle M, while another object (parked vehiclePv in FIG. 11 ) faces the side 41 b opposing the side 41 a close to thevehicle M. In FIGS. 10 through 15 , a side of the virtual parking region41 that an object does not face is set to be a side 41 a, while a sideof the virtual parking region 41 that an object faces is set to be aside 41 b. In one embodiment, processing in step S26 described above andprocessing in step S32, which will be discussed later, may correspond toprocessing of an “object detector”.

A mode in which an object faces each of the three sides of the virtualparking region 41 other than the side close to the vehicle M is a stateillustrated in FIG. 13 . In FIG. 13 , the three sides other than theside that a vehicle enters and exists from are surrounded by objects(parked vehicles Pv in FIG. 13 ). A mode in which an object faces oneside of the virtual parking region 41 other than the side close to thevehicle M is a state of parking space candidates Ps5 and Ps6 illustratedin FIG. 9 . As illustrated in FIG. 9 , there is a large space (parkingspace candidates Ps5 and Ps6) between adjacent objects (parked vehiclesPv) and two virtual parking regions 41 are set between the adjacentparked vehicles Pv. Details of parking space candidates will bediscussed later.

In step S27, the driving assist control unit 11 checks whether thefootprints 51 detected in the virtual parking region 41 continuouslyextend and intersect (cross) the two sides 41 a which no object faces.If an object faces each of the two sides 41 b of a virtual parkingregion 41, one of the sides 41 a which no object faces is the side closeto the vehicle M. The two sides 41 a which no object faces may be theside 41 a close to the vehicle M and the opposing side 41 a, asillustrated in FIG. 10 , or the side close to the vehicle M and theadjacent side 41 a, as illustrated in FIG. 11 . If the footprints 51continuously extend from the side 41 a close to the vehicle M andintersect (cross) the other side 41 a, the driving assist control unit11 determines that the currently set virtual parking region 41 is likelyto be a sidewalk. The driving assist control unit 11 then proceeds tostep S29.

As illustrated in FIG. 12 , when no object faces the side 41 a close tothe vehicle M and the opposing (or adjacent) side 41 a and whenfootprints 51 only intersect (cross) the side 41 a close to the vehicleM, the driving assist control unit 11 determines that the footprints 51detected in the currently set virtual parking region 41 are likely to bethose left by an occupant having got in and out of a parked vehicle andbranches off to step S30.

In step S28, the driving assist control unit 11 determines whether thefootprints 51 only cross the side 41 a close to the vehicle M. Asdiscussed above, even when a object faces only one side other than theside 41 a close to the vehicle M, if the footprints 51 only cross theside 41 a close to the vehicle M, the driving assist control unit 11determines that the footprints 51 in the currently set virtual parkingregion 41 are likely to be those left by an occupant of a vehicle havingparked in the space corresponding to the virtual parking region 41. If aobject faces each of the three sides 41 b of the virtual parking region41 other than the side 41 a close to the vehicle M, the virtual parkingregion 41 is likely to be a space where the vehicle M can park. Even inthis case, by checking whether the footprints 51 only cross the side 41a close to the vehicle M, the driving assist control unit 11 candetermine with higher accuracy whether the vehicle M can park in thisspace.

If it is determined in step S28 that the footprints 51 only cross theside 41 a close to the vehicle M, the driving assist control unit 11determines that the footprints 51 are those of an occupant having got inand out of a parked vehicle Pv and proceeds to step S30. If thefootprints 51 cross a side 41 a which no object faces, the drivingassist control unit 11 determines that the currently set virtual parkingregion 41 is less likely to be a parking space and proceeds to step S29.If the driving assist control unit 11 shifts from step S27 or S28 tostep S29, it sets the parking priority to be low since the currently setvirtual parking region 41 is less likely to be a parking space. Thedriving assist control unit 11 then proceeds to step S36. If the drivingassist control unit 11 shifts from step S27 or S28 to step S30, it setsthe parking priority to be high (recommended) since the currently setvirtual parking region 41 is likely to be a parking space. The drivingassist control unit 11 then proceeds to step S36. In one embodiment,processing in steps S26 through 30 described above and processing insteps S32 through 35, which will be discussed later, may correspond toprocessing of a “parking priority setter”.

If the driving assist control unit 11 shifts from step S25 to step S31,based on the front-side environment information obtained from thefront-side recognition sensor 21 and thefront-left-side/front-right-side environment information obtained fromthe front-left-side/front-right-side sensors 27, the driving assistcontrol unit 11 determines whether tire tracks 101 are detected as amovement trace in the virtual parking region 41 set in step S24. Tiretracks 101 are detected in the following manner, for example. Based onthe front-side environment information andfront-left-side/front-right-side environment information, the luminancedifference generated on steps (edges) on the snow surface or mud surfacedue to the presence of possible tire tracks or a change in the intensity(reflectance) of light or waves reflected by the snow surface or mudsurface is found. Then, based on the luminance difference orreflectance, known pattern matching, for example, is performed on aseries of feature points representing the edges of possible tire tracks,thereby recognizing the tire tracks 101.

If tire tracks 101 are detected, the driving assist control unit 11proceeds to step S32. If tire tracks 101 are not detected, the drivingassist control unit 11 proceeds to step S34. In step S32, based on theabove-described front-side environment information andfront-left-side/front-right-side environment information, the drivingassist control unit 11 determines whether an object (parked vehicle Pvor outer wall) faces each of the three sides of the virtual parkingregion 41 other than the side 41 a close to the vehicle M. If an objectfaces each of the three sides of the virtual parking region 41, thedriving assist control unit 11 proceeds to step S34. As illustrated inFIG. 13 , if the three sides 41 b other than the side 41 a close to thevehicle M are surrounded by objects, the tire tracks 101 detected in thevirtual parking region 41 are those left when a vehicle has entered andexited from the space of the virtual parking region 41, and the drivingassist control unit 11 can determine that this space is likely to be aparking space.

If an object faces only one side or two sides of the virtual parkingregion 41 other than the side 41 a close to the vehicle M, the drivingassist control unit 11 branches off to step S33. There are two modes inwhich an object (parked vehicle Pv in FIGS. 14 and 15 ) faces each oftwo sides other than the side 41 a close to the vehicle M. One mode isthat, as illustrated in FIG. 14 , objects (parked vehicles Pv) face thetwo sides 41 b adjacent to the side 41 a close to the vehicle M. Theother mode is that, as illustrated in FIG. 15 , an object (parkedvehicle Pv) faces one of the two sides 41 b adjacent to the side 41 aclose to the vehicle M, while another object (parked vehicle Pv) facesthe side 41 b opposing the side 41 a close to the vehicle M.

In step S33, the driving assist control unit 11 checks whether tiretracks 101 intersect (cross) the two sides 41 a which no object faces.If, as illustrated in FIGS. 14 and 15 , the tire tracks 101 continuouslycross the side 41 a close to the vehicle M and the other side 41 a, thedriving assist control unit 11 determines that the currently set virtualparking region 41 is likely to be a driving lane and proceeds to stepS35.

If the tire tracks 101 do not cross the two sides 41 a of the virtualparking regions 41, that is, if the tire tracks 101 only cross the side41 a close to the vehicle M, the driving assist control unit 11determines that the tire tracks 101 are those left when a vehicle isparked and that the virtual parking region 41 is likely to be a parkingspace. The driving assist control unit 11 then proceeds to step S34.When an object faces only one side 41 b other than the side 41 a closeto the vehicle M, the driving assist control unit 11 makes adetermination in the following manner. If the tire tracks 101 cross twosides 41 a which no object faces, the driving assist control unit 11determines that the virtual parking region 41 is likely to be a drivinglane. If the tire tracks 101 only cross the side 41 a close to thevehicle M, the driving assist control unit 11 determines that thevirtual parking region 41 is likely to be a parking space.

If the driving assist control unit 11 shifts from one of steps S31through S33 to step S34, it sets the parking priority to be high sincethe currently set virtual parking region 41 is likely to be a parkingspace. The driving assist control unit 11 then proceeds to step S36. Ifthe driving assist control unit 11 shifts from step S33 to step S35, itsets the parking priority to be low since the currently set virtualparking region 41 is likely to be a driving lane. The driving assistcontrol unit 11 then proceeds to step S36.

When the driving assist control unit 11 shifts from one of steps S29,S30, S34, and S35 to step S36, the driving assist control unit 11determines whether the parking priority has been set for all the virtualparking regions 41 which have been determined to be parking capablespaces based on the above-described front-side environment informationand front-left-side/front-right-side environment information. If theparking priority has not been set for all the virtual parking regions41, the driving assist control unit 11 returns to step S22 in FIG. 4 tosearch for the next candidate of the virtual parking region 41. If theparking priority has been set for all the virtual parking regions 41,the driving assist control unit 11 proceeds to step S37.

In step S37, the driving assist control unit 11 sets the virtual parkingregions 41 to be parking space candidates Ps by linking the associatedparking priorities to the virtual parking regions 41 and displays theparking space candidates together on the HMI monitor 31. In this case,as illustrated in FIG. 8 , for example, the driving assist control unit11 displays recommended parking space candidates Ps having a highparking priority in blue (indicated by the thick lines in FIG. 8 ) andparking space candidates Ps having a low parking priority in orange(indicated by the thin lines in FIG. 8 ) so that the driver caninstantly visually distinguish them from each other. As illustrated inFIG. 9 , parking space candidates Ps1 through Ps6 set on the left andright sides of the driving lane where the vehicle M is driving are alldisplayed on the HMI monitor 31 in a bird's eye view.

Then, the driving assist control unit 11 proceeds to step S38 to drivethe notifying device 33 to output a voice message to instruct the driverto select one of the parking space candidates Ps (Ps1 through Ps6 inFIG. 8 ) displayed on the HMI monitor 31. In step S39, the drivingassist control unit 11 determines which one of the parking spacecandidates Ps the driver has selected. The driver can select a desiredparking space candidate Ps by touching it displayed on the HMI monitor31.

If it is determined in step S39 that the driver has selected one of theparking space candidates Ps, the driving assist control unit 11 proceedsto step S40. If a predetermined time has elapsed after the voice messageis output or if the vehicle M has passed by the parking space candidatesPs displayed on the HMI monitor 31, the driving assist control unit 11branches off to step S44.

The driving assist control unit 11 checks in step S40 whether the driverhas selected a parking space candidate Ps (one of the parking spacecandidates Ps1 through Ps3 in FIG. 8 ) having a low parking priority. Ifthe driver has selected a parking space candidate Ps (one of the parkingspace candidates Ps4 through Ps6) having a high parking priority, thedriving assist control unit 11 proceeds to step S43. If the driver hasselected a parking space candidate Ps having a low priority, the drivingassist control unit 11 proceeds to step S41.

The driver may have selected a parking space candidate Ps having a lowpriority by mistake. Thus, in step S41, the driving assist control unit11 drives the notifying device 33 to output a voice message to checkwhether the driver has intended to select the parking space candidate Pshaving a low priority. In this manner, when a driver has selected aparking space candidate Ps having a low priority, a voice message isoutput to ascertain whether the driver has intended to select thisparking space. This can decrease the possibility that the driver wronglyguides the vehicle M to a sidewalk or a driving lane where parking isprohibited, thereby reducing the burden on the driver.

Then, the driving assist control unit 11 proceeds to step S42 to checkwhether the driver has changed the parking space candidate Ps. Thedriver can change the parking space candidate Ps by touching one of theparking space candidates Ps (Ps1 through Ps6 in FIG. 8 ) displayed onthe HMI monitor 31. If the driver has changed the parking spacecandidate Ps, the driving assist control unit 11 returns to step S40. Ifa predetermined time has elapsed after the voice message is output orthe driver has touched a setting button displayed on the HMI monitor 31,the driving assist control unit 11 determines that the driver has notchanged the parking space candidate Ps and proceeds to step S43.

For example, even though the driving assist control unit 11 sets theparking priority of the parking space candidate Ps1 to be low since thefootprints 51 cross the two sides of a virtual parking region 41, asillustrated in FIG. 9 , the driver may visually check the parking spacecandidate Ps1 and determine that it is apparently a parking space. Insuch a situation, if the driving assist control unit 11 excludes theparking space candidate Ps1 from parking space candidates to bedisplayed on the HMI monitor 31, the results determined by the drivingassist control unit 11 become different from the recognition results ofthe driver. This lowers the reliability in processing executed by thedriving assist control unit 11. In the embodiment, the parking priorityis linked to a parking space candidate Ps, which gives the driver morechoices for a parking space candidate, thereby implementing a high levelof parking assist. In one embodiment, processing in steps S37 throughS42 may correspond to processing of a “display selector”.

If the driving assist control unit 11 proceeds from step S40 or S42 tostep S43, it sets the parking space candidate Ps selected by the driver(Ps4 in FIG. 8 , for example) to a target parking space Pt and proceedsto step S45. In step S45, the driving assist control unit 11 executesautomatic parking control to park the vehicle M in the target parkingspace Pt and completes the routine.

If it is determined in step S39 that the driver has not selected anyparking space candidate Ps after the lapse of the predetermined time orthe vehicle M has passed by the parking space candidates Ps displayed onthe HMI monitor 31, the driving assist control unit 11 branches off tostep S44 and clears all the parking space candidates Ps displayed on theHMI monitor 31. The driving assist control unit 11 then proceeds to stepS46.

In step S46, the driving assist control unit 11 determines whether theparking assist mode is OFF. If the parking assist mode is found to beOFF, the driving assist control unit 11 exits from the routine. If theparking assist mode is found to be ON, the driving assist control unit11 returns to step S22 in FIG. 4 . The parking assist mode is turned OFFwhen the driver has performed a certain operation using a certaindevice, such as the HMI monitor 31. The parking assist mode isautomatically turned OFF when the driving assist control unit 11 hasdetected that the vehicle M has exited from the parking lot.

Automatic parking control executed by the driving assist control unit 11in step S45 will be briefly discussed below. As illustrated in FIG. 9 ,a target parking guiding route Gr for guiding the vehicle M to thetarget parking space Pt is first formed. The target parking guidingroute Gr is set so that the widthwise center of the vehicle M matchesthat of the target parking space Pt. If, for example, the parking spacewidth Wp between objects (parked vehicles Pv) is larger than thesufficient parking width Ws in the target parking space Pt by apredetermined factor or greater (1.5 times, for example), the edge ofthe sufficient parking width Ws on the side of the driver's seat of thevehicle M may be shifted toward the adjacent object (parked vehicle Pv),and then, the target parking space Pt may be set. Then, the targetparking guiding route Gr may be formed so that the widthwise center ofthe vehicle M matches that of the target parking space Pt.

Then, the driving assist control unit 11 performs control toautomatically park the vehicle M in the target parking space Pt asdetermined above and exits from the routine. The target parking guidingroute Gr is set similarly to when it is set under the normal conditionwhere the lines of parking spaces are recognized.

As a result of the vehicle M driving around the driving lane of theparking lot, information on the overall positions of the vehicles Pvparked in the parking lot can be obtained, and based on thisinformation, parking space candidates Ps may be set in the entireparking lot.

As discussed above, in the embodiment, when assisting a vehicle M inautomatically parking in a parking space of a parking lot under a poorenvironment where the lines of parking spaces are not recognized due tosnow or mud, the parking space width Wp between adjacent objects (parkedvehicles Pv or walls) is compared with the sufficient parking width Wsof a virtual parking region 41 set for the vehicle M. If the parkingspace width Wp is greater than or equal to the sufficient parking widthWs (WpWs), a virtual parking region 41 is set in the parking spacehaving the parking space width Wp. Then, the parking priority is set forthe parking space, based on the presence or the absence of footprints 51or tire tracks 101 and how they are left in the virtual parking region41 and the facing direction of an object along the virtual parkingregion 41. As a result, parking space candidates Ps (Ps1 through Ps6 inFIG. 8 ) obtained by linking the associated parking priorities to thevirtual parking region 41 are displayed together on the HMI monitor 31.A driver can thus select a desired one of the displayed parking spacecandidates Ps (Ps1 through Ps6) at one time, thereby reducing the burdenon the driver.

Since the parking priority is linked to each parking space candidate Ps,the driver can easily recognize a parking capable space. Even for aparking space candidate Ps having a low parking priority, the driver canchoose this parking space candidate Ps if he/she determines that it is aparking capable space. This gives the driver more choices for a parkingspace candidate Ps, thereby implementing a high level of parking assist.

The disclosure is not restricted to the above-described embodiment. Forexample, the driver may drive around a parking lot by himself/herselfand look for a parking space in which a virtual parking region 41 can beaccommodated while visually checking the HMI monitor 31. Then, when thedriver specifies such a parking space, he/she may stop the vehicle M infront of the specified parking space and select the parking assist mode.In response to this selection, the driving assist control unit 11 maycheck the parking priority for this parking space and inform the driverof the result.

Additionally, in step S45, the target parking guiding route Gr may bedisplayed on the HMI monitor 31 such that it is superimposed on a planview of the surroundings of a parking space where the vehicle M is to beparked, and the driver may park the vehicle M by himself/herself inaccordance with the target parking guiding route Gr.

According to an embodiment of the disclosure, a parking space candidateis set by linking the parking priority to a virtual parking region.Plural parking space candidates set in this manner are displayedtogether using a display selector so that a driver can select one ofthem. With this configuration, when assisting a vehicle in parking in aparking space using a parking assist function, a driver is not askedwhether to select a parking space every time a parking space betweenparked vehicles is detected under a poor environment where the lines ofa parking space are not recognized, thereby reducing the burden on thedriver.

The driving assist control unit 11 illustrated in FIG. 1 can beimplemented by circuitry including at least one semiconductor integratedcircuit such as at least one processor (e.g., a central processing unit(CPU)), at least one application specific integrated circuit (ASIC),and/or at least one field programmable gate array (FPGA). At least oneprocessor can be configured, by reading instructions from at least onemachine readable tangible medium, to perform all or a part of functionsof the driving assist control unit 11 including the driving assist modeand the parking assist mode. Such a medium may take many forms,including, but not limited to, any type of magnetic medium such as ahard disk, any type of optical medium such as a CD and a DVD, any typeof semiconductor memory (i.e., semiconductor circuit) such as a volatilememory and a non-volatile memory. The volatile memory may include a DRAMand a SRAM, and the non-volatile memory may include a ROM and a NVRAM.The ASIC is an integrated circuit (IC) customized to perform, and theFPGA is an integrated circuit designed to be configured aftermanufacturing in order to perform, all or a part of the functions of themodules illustrated in FIG. 1 .

1. A parking assist system configured to guide a vehicle to a parkingcapable space in a parking lot, the parking assist system comprising: anenvironment information obtainer configured to obtain environmentinformation on an environment around the vehicle; a storage configuredto store data on a virtual parking region to be used for parking thevehicle; a parking space width calculator configured to calculate awidth of a parking space between objects, based on the environmentinformation obtained by the environment information obtainer; a parkingwidth comparator configured to compare the width of the parking spacewith a width of the virtual parking region stored in the storage; avirtual parking region setter configured to set the virtual parkingregion in the parking space in a case where the parking width comparatorhas determined that the width of the parking space is larger than orequal to the width of the virtual parking region; a movement tracedetector configured to detect a movement trace within the set virtualparking region set by the virtual parking region setter, based on theenvironment information obtained by the environment informationobtainer; an object detector configured to determine whether an objectof the objects faces at least one of sides of the virtual parking regionother than a side of the virtual parking region close to the vehicle; aparking priority setter configured to set a parking priority for thevirtual parking region in accordance with the movement trace detected bythe movement trace detector and the object which faces the virtualparking region detected by the object detector; a display selectorconfigured to display parking space candidates together to instruct adriver of the vehicle to select a parking space candidate, the parkingspace candidates including the parking space candidate obtained bylinking the parking priority set by the parking priority setter to thevirtual parking region set by the virtual parking region setter; and aparking assister configured to set the parking space candidate selectedby the driver using the display selector to a target parking space andto guide the vehicle to the target parking space.
 2. The parking assistsystem according to claim 1, wherein, in a case where the movement tracedetected by the movement trace detector continuously crosses two sidesof the virtual parking region, the parking priority setter sets theparking priority for the virtual parking region to be low.
 3. Theparking assist system according to claim 1, wherein, in a case where themovement trace detected by the movement trace detector only crosses theside of the virtual parking region close to the vehicle, the parkingpriority setter sets the parking priority for the virtual parking regionto be high.
 4. The parking assist system according to claim 1, wherein,in a case where the objects face two sides of the virtual parking regionother than the side close to the vehicle and the movement trace detectedby the movement trace detector continuously crosses two sides of thevirtual parking region, the parking priority setter sets the parkingpriority for the virtual parking region to be low.
 5. The parking assistsystem according to claim 1, wherein, in a case where the driver hasselected the parking space candidate having a low parking priority, thedisplay selector checks with the driver whether the driver has intendedto select the parking space candidate having the low parking priority.6. The parking assist system according to claim 2, wherein, in a casewhere the driver has selected the parking space candidate having a lowparking priority, the display selector checks with the driver whetherthe driver has intended to select the parking space candidate having thelow parking priority.
 7. The parking assist system according to claim 3,wherein, in a case where the driver has selected the parking spacecandidate having a low parking priority, the display selector checkswith the driver whether the driver has intended to select the parkingspace candidate having the low parking priority.
 8. The parking assistsystem according to claim 4, wherein, in a case where the driver hasselected the parking space candidate having a low parking priority, thedisplay selector checks with the driver whether the driver has intendedto select the parking space candidate having the low parking priority.9. A parking assist system configured to guide a vehicle to a parkingcapable space in a parking lot, the parking assist system comprising: asensor configured to obtain environment information on an environmentaround the vehicle; a storage configured to store data on a virtualparking region to be used for parking the vehicle; and circuitryconfigured to calculate a width of a parking space between objects,based on the environment information obtained by the sensor, compare thecalculated width of the parking space between the objects with a widthof the virtual parking region stored in the storage, set the virtualparking region in the parking space in a case where the width of theparking space is found to be larger than or equal to the width of thevirtual parking region, detect a movement trace within the set virtualparking region, based on the environment information obtained by theobtainer, determine whether an object of the objects faces at least oneof sides of the virtual parking region other than a side of the virtualparking region close to the vehicle, set a parking priority for thevirtual parking region in accordance with the detected movement traceand the detected object which faces the virtual parking region, displayparking space candidates together to instruct a driver of the vehicle toselect a parking space candidate, the parking space candidates includethe parking space candidate obtained by linking the parking priority tothe virtual parking region, and set the parking space candidate selectedby the driver to a target parking space to guide the vehicle to thetarget parking space.